#include "mainwindow.h"
#include <QtWidgets>
#include <QFile>
#include <QDir>
#include <QGuiApplication>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent),
      textEdit(new QPlainTextEdit())
{
    setCentralWidget(textEdit);
    createActions();
    createStatusBar();
    readSettings();
    connect(textEdit->document(), &QTextDocument::contentsChanged,
                this, &MainWindow::documentWasModified);

    #ifndef QT_NO_SESSIONMANAGER
        QGuiApplication::setFallbackSessionManagementEnabled(false);
        connect(qApp, &QGuiApplication::commitDataRequest,
                this, &MainWindow::commitData);
    #endif

        setCurrentFile(QString());
        setUnifiedTitleAndToolBarOnMac(true);
}

MainWindow::~MainWindow()
{
}

void MainWindow::createActions(){
    QMenu *fileMenu = menuBar()->addMenu("&File");
    QToolBar *fileToolBar = addToolBar("File");

    const QIcon newIcon = QIcon::fromTheme("document-new", QIcon(":/images/new.png"));
    QAction *newAct = new QAction(newIcon, tr("&New"), this);
        newAct->setShortcuts(QKeySequence::New);
        newAct->setStatusTip(tr("Create a new file"));
        connect(newAct, &QAction::triggered, this, &MainWindow::newFile);
        fileMenu->addAction(newAct);
        fileToolBar->addAction(newAct);

    //! [19]
        const QIcon openIcon = QIcon::fromTheme("document-open", QIcon(":/images/open.png"));
        QAction *openAct = new QAction(openIcon, tr("&Open..."), this);
        openAct->setShortcuts(QKeySequence::Open);
        openAct->setStatusTip(tr("Open an existing file"));
        connect(openAct, &QAction::triggered, this, &MainWindow::open);
        fileMenu->addAction(openAct);
        fileToolBar->addAction(openAct);
    //! [18] //! [19]

        const QIcon saveIcon = QIcon::fromTheme("document-save", QIcon(":/images/save.png"));
        QAction *saveAct = new QAction(saveIcon, tr("&Save"), this);
        saveAct->setShortcuts(QKeySequence::Save);
        saveAct->setStatusTip(tr("Save the document to disk"));
        connect(saveAct, &QAction::triggered, this, &MainWindow::save);
        fileMenu->addAction(saveAct);
        fileToolBar->addAction(saveAct);

        const QIcon saveAsIcon = QIcon::fromTheme("document-save-as");
        QAction *saveAsAct = fileMenu->addAction(saveAsIcon, tr("Save &As..."), this, &MainWindow::saveAs);
        saveAsAct->setShortcuts(QKeySequence::SaveAs);
        saveAsAct->setStatusTip(tr("Save the document under a new name"));

    //! [20]

        fileMenu->addSeparator();

        const QIcon exitIcon = QIcon::fromTheme("application-exit");
        QAction *exitAct = fileMenu->addAction(exitIcon, tr("E&xit"), this, &QWidget::close);
        exitAct->setShortcuts(QKeySequence::Quit);
    //! [20]
        exitAct->setStatusTip(tr("Exit the application"));

    //! [21]
        QMenu *editMenu = menuBar()->addMenu(tr("&Edit"));
        QToolBar *editToolBar = addToolBar(tr("Edit"));
    //!
    #ifndef QT_NO_CLIPBOARD
        const QIcon cutIcon = QIcon::fromTheme("edit-cut", QIcon(":/images/cut.png"));
        QAction *cutAct = new QAction(cutIcon, tr("Cu&t"), this);
    //! [21]
        cutAct->setShortcuts(QKeySequence::Cut);
        cutAct->setStatusTip(tr("Cut the current selection's contents to the "
                                "clipboard"));
        connect(cutAct, &QAction::triggered, textEdit, &QPlainTextEdit::cut);
        editMenu->addAction(cutAct);
        editToolBar->addAction(cutAct);

        const QIcon copyIcon = QIcon::fromTheme("edit-copy", QIcon(":/images/copy.png"));
        QAction *copyAct = new QAction(copyIcon, tr("&Copy"), this);
        copyAct->setShortcuts(QKeySequence::Copy);
        copyAct->setStatusTip(tr("Copy the current selection's contents to the "
                                 "clipboard"));
        connect(copyAct, &QAction::triggered, textEdit, &QPlainTextEdit::copy);
        editMenu->addAction(copyAct);
        editToolBar->addAction(copyAct);

        const QIcon pasteIcon = QIcon::fromTheme("edit-paste", QIcon(":/images/paste.png"));
        QAction *pasteAct = new QAction(pasteIcon, tr("&Paste"), this);
        pasteAct->setShortcuts(QKeySequence::Paste);
        pasteAct->setStatusTip(tr("Paste the clipboard's contents into the current "
                                  "selection"));
        connect(pasteAct, &QAction::triggered, textEdit, &QPlainTextEdit::paste);
        editMenu->addAction(pasteAct);
        editToolBar->addAction(pasteAct);

        menuBar()->addSeparator();

    #endif // !QT_NO_CLIPBOARD

        QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
        QAction *aboutAct = helpMenu->addAction(tr("&About"), this, &MainWindow::about);
        aboutAct->setStatusTip(tr("Show the application's About box"));

    //! [22]

        QAction *aboutQtAct = helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
        aboutQtAct->setStatusTip(tr("Show the Qt library's About box"));
    //! [22]

    //! [23]
    #ifndef QT_NO_CLIPBOARD
        cutAct->setEnabled(false);
    //! [23] //! [24]
        copyAct->setEnabled(false);
        connect(textEdit, &QPlainTextEdit::copyAvailable, cutAct, &QAction::setEnabled);
        connect(textEdit, &QPlainTextEdit::copyAvailable, copyAct, &QAction::setEnabled);
    #endif // !QT_NO_CLIPBOARD

}

void MainWindow::createStatusBar()
//! [32] //! [33]
{
    statusBar()->showMessage(tr("Ready"));
}

void MainWindow::loadFile(const QString &fileName){
    QFile file(fileName);
    if (!file.open(QFile::ReadOnly|QFile::Text)){
        QMessageBox::warning(this,"Application",tr("cannot read file %1,%2").arg(QDir::toNativeSeparators(fileName),file.errorString()));
        return;
    }
    QTextStream in(&file);
#ifndef QT_NO_CURSOR
    QGuiApplication::setOverrideCursor(Qt::WaitCursor);
   #endif
    textEdit->setPlainText(in.readAll());
#ifndef QT_NO_CURSOR
    QGuiApplication::restoreOverrideCursor();
#endif
    setCurrentFile(fileName);
    statusBar()->showMessage("file Loaded", 2000);
}

void MainWindow::setCurrentFile(const QString &fileName){
    this->curFile = fileName;
}

void MainWindow::closeEvent(QCloseEvent *event){
    if (maybeSave()) {
              writeSettings();
              event->accept();
          } else {
              event->ignore();
          }
}

void MainWindow::newFile(){
    if (maybeSave()){
        textEdit->clear();
        setCurrentFile(QString());
    }
}

void MainWindow::open(){
    if (maybeSave()){
        QString fileName = QFileDialog::getOpenFileName(this);
        if (!fileName.isEmpty()){
            loadFile(fileName);
        }
    }
}

bool MainWindow::save(){
    if (curFile.isEmpty()){
        return saveAs();
    } else {
        return saveFile(curFile);
    }
}

bool MainWindow::saveAs(){
    QFileDialog dialog(this);
    dialog.setWindowModality(Qt::WindowModal);
    dialog.setAcceptMode(QFileDialog::AcceptSave);
    if (dialog.exec() != QDialog::Accepted)
        return false;
    return saveFile(dialog.selectedFiles().first());
}

bool MainWindow::saveFile(const QString &fileName) {
    QFile file(fileName);
    if (!file.open(QFile::WriteOnly|QFile::Text)){
        QMessageBox::warning(this, tr("Application"),
                                       tr("Cannot write file %1:\n%2.")
                                       .arg(QDir::toNativeSeparators(fileName),
                                            file.errorString()));
                  return false;
    }
    QTextStream out(&file);
#ifndef QT_NO_CURSOR
    QGuiApplication::setOverrideCursor(Qt::WaitCursor);
#endif
    out << textEdit->toPlainText();
#ifndef QT_NO_CURSOR
    QGuiApplication::restoreOverrideCursor();
#endif

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File saved"), 2000);
    return true;
}

bool MainWindow::maybeSave(){
    if (!textEdit->document()->isModified()){
        return true;
    }
    const QMessageBox::StandardButton ret
              = QMessageBox::warning(this, tr("Application"),
                                     tr("The document has been modified.\n"
                                        "Do you want to save your changes?"),
                                     QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
    switch (ret){
    case QMessageBox::Save:
        return save();
    case QMessageBox::Cancel:
        return false;
    default:
        break;
    }
    return true;
}

void MainWindow::about(){
    QMessageBox::about(this, tr("About Application"),
                 tr("The <b>Application</b> example demonstrates how to "
                    "write modern GUI applications using Qt, with a menu bar, "
                    "toolbars, and a status bar."));
}

void MainWindow::documentWasModified()
{
    setWindowModified(textEdit->document()->isModified());
}

void MainWindow::readSettings()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());
    const QByteArray geometry = settings.value("geometry", QByteArray()).toByteArray();
    if (geometry.isEmpty()) {
        const QRect availableGeometry = QApplication::desktop()->availableGeometry(this);
        resize(availableGeometry.width() / 3, availableGeometry.height() / 2);
        move((availableGeometry.width() - width()) / 2,
             (availableGeometry.height() - height()) / 2);
    } else {
        restoreGeometry(geometry);
    }
}

void MainWindow::writeSettings()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());
    settings.setValue("geometry", saveGeometry());
}

#ifndef QT_NO_SESSIONMANAGER
void MainWindow::commitData(QSessionManager &manager)
{
    if (manager.allowsInteraction()) {
        if (!maybeSave())
            manager.cancel();
    } else {
        // Non-interactive: save without asking
        if (textEdit->document()->isModified())
            save();
    }
}
#endif
